1. Technical Field
The present invention relates to a control device for controlling an electric vehicle which is provided with a driving source such as a traction motor (electric motor).
2. Related Art
For example, electric vehicles such as electric vehicles or hybrid vehicles heretofore have traction motors (electric motors) etc. provided as driving sources. According to a configuration of one of the traction motors provided in the electric vehicles, the traction motor generates plus-side driving force (torque) for making the electric vehicle travel by use of electric power from a battery, and on the other hand, the traction motor is operated as a power generator during deceleration etc. to generate minus-side regenerative force (torque). In addition, in some of the electric vehicles, a creep phenomenon caused by a torque converter of an engine vehicle is simulated in a predetermined low-speed region, and so-called creep torque is generated in the traction motor even when an accelerator pedal is OFF.
The creep torque is generated also during stopping of the vehicle. However, the creep torque is set at a magnitude enough to keep the electric vehicle at the stopping state when a brake pedal is depressed by a predetermined amount or more. Therefore, energy (electric power) for generating the creep torque during stopping of the vehicle is wastefully consumed. In order to suppress such a waste of energy, there has been proposed a technique for suppressing creep torque in accordance with a depression amount of a brake pedal.
In recent years, there has been developed an electric vehicle in which control (brake auto-hold control) for keeping braking force during stopping of the vehicle at a predetermined value is executed even in a state in which a brake pedal has not been depressed. There has been also proposed a technique for suppressing creep torque to zero when the control for keeping the braking force during stopping of the vehicle is in execution as described above (e.g. see Japanese Patent No. 4127310).
According to the technique described in Japanese Patent No. 4127310, it is possible to suppress wasteful consumption of energy (electric power).
However, as to the electric vehicle in which the creep torque is reduced to zero during stopping of the vehicle, as described in Japanese Patent No. 4127310, there is a fear that the electric vehicle may move backward when, for example, depression of the brake pedal is too shallow during stopping of the vehicle on an uphill road, to make it impossible to keep the electric vehicle at the stopping state.
Such a problem may occur even in a state in which the brake pedal has been depressed. Particularly, such a problem is apt to occur when the brake auto-hold control in which the brake pedal has not been depressed is in execution.
The invention has been accomplished in consideration of such circumstances. An object of the invention is to provide a control device for controlling an electric vehicle, which can suppress wasteful consumption of energy and keep the electric vehicle at a stopping state suitably.